1. Field of the Invention
The present invention relates to a valved connection member favorably usable in an evaporation piping system of an automobile fuel tank, etc. and to a connection structure using the valved connection member.
2. Description of the Related Art
The internal pressure of an automobile fuel tank built up by evaporated gasoline is controlled through connection of the fuel tank and a canister located on the engine side by means of piping. Specifically, a check valve is installed in an evaporation line connecting the fuel tank and the canister so as to allow flow of evaporated gasoline from the fuel tank to the engine but not in the reverse direction.
Conventionally, the fuel tank and the check valve are connected by means of a rubber hose, and the check valve and the canister are also connected by means of a rubber hose. Connections are each clamped from outside the rubber hose by means of a clamp member, such as a clip. However, such connection practice involves an increase in the number of components and very complicated connection work, resulting in increased cost.
According to recent tendencies, in order to suppress permeation of gasoline and to improve connection workability, a resin tube is used in place of a rubber hose. Resin tubes are used in the following manner. Resin tubes are connected to corresponding opposite ends of the check valve, and quick connectors are connected to the respective free ends of the resin tubes. The quick connectors are used for connection to the fuel tank and the canister.
A conventionally used check valve is configured such that a valve body is movably disposed within a substantially cylindrical housing, while being biased toward a valve seat formed at one end of the housing by means of a valve spring. Accordingly, the conventional check valve is a separate member from the quick connector and the rubber hose or resin tube and is press-fitted, for use, into an end portion of the rubber hose or the resin tube. Also, assembly of the check valve is complicated in terms of process and accuracy; for example, welding upper and lower housing halves is required.
As mentioned above, since the check valve to be installed in, for example, an evaporation piping system of an automobile fuel tank, is a separate member from the quick connector and the rubber hose or resin tube, the number of components increases and connection work becomes complicated, resulting in difficulty in reducing cost.
In order to meet recent requirements for further reduction in gasoline permeability, even very small permeation from a connection between the rubber hose or the resin tube and the check valve cannot be disregarded. Thus, a reduction in connections between components is an effective means for suppression permeation of gasoline.
An object of the present invention is to solve the above-mentioned problems, and to provide a connection member of simple structure equipped with a check valve allowing a reduction in the number of components of a piping system, such as an evaporation piping system, that requires installation of a check valve, and a reduction in the number of connections, as well as to provide a connection structure of low gasoline permeability and low cost favorably usable in, for example, an evaporation piping system employing a valved connection member.
To achieve the above object, according to a first aspect of the present invention, a connection structure comprises a valved connection member and a flexible tube connected to the valved connection member. The valved connection member comprises a cylindrical connection member, a cylindrical valve cap, a cylindrical valve body, and a compression spring. The cylindrical connection member comprises a cylindrical nipple portion formed at one end and allowing the inner circumferential surface of an end portion of the flexible tube to be fitted thereto; and an annular first end face portion formed at an end part of the nipple portion in such a manner as to face toward the one end and to extend radially. The cylindrical valve cap comprises a small-diameter portion and a large-diameter portion, an axial bore formed in the small-diameter portion being smaller in diameter than an axial bore formed in the large-diameter portion; a valve seat portion having a valve seal surface formed on the inner circumferential surface of the cylindrical valve cap and located between the small-diameter portion and the large-diameter portion; and a fitting end portion formed at one end of the large-diameter portion away from the small-diameter portion and fitted to the outer circumferential surface of the end part of the nipple portion of the connection member. The cylindrical valve body comprises a bottom portion having an abutment part to abut the valve seal surface of the valve cap; a cylindrical open end portion extending from the bottom portion and opening toward the connection member; an annular second end face portion formed at the open end portion in such a manner as to face the first end face portion and to extend radially; a first sliding portion extending radially outward from the open end portion in an integral condition; and a first flow path portion provided in the first sliding portion and allowing flow of fluid. The valve body is accommodated within the large-diameter portion of the valve cap in such a manner as to be axially slidable by virtue of the first sliding portion. The compression spring is disposed between the first end face portion and the second end face portion and adapted to bias the valve body toward the valve seal surface. One end portion of the flexible tube is fitted to the outer circumferential surface of the valve cap fitted to the outer circumferential surface of the end part of the nipple portion of the connection member and is further fitted to the outer circumferential surface of the nipple portion extending away from the outer circumferential surface of the valve cap.
According to the first aspect of the present invention, since the valve body is biased toward the valve seat portion by means of the compression spring, the abutment part of the bottom portion of the valve body is in close contact with the valve seal surface of the valve cap. Accordingly, when the upstream fluid pressure of the connection structure is lower than the downstream fluid pressure, a flow path including the first flow path portion is closed to thereby disable flow of fluid. In contrast, when the upstream fluid pressure becomes higher than the downstream fluid pressure, the valve body moves toward the connection member against the compression spring. Thus, the abutment part of the bottom portion of the valve body moves away from the valve seal surface and toward the connection member, thereby forming a gap between the abutment part and the valve seal surface. As a result, the flow path including the first flow path portion is opened to thereby permit downstream flow of fluid. In this case, the valve body can smoothly move within the large-diameter portion in the axial direction by virtue of the first sliding portion. Also, the first flow path portion provided in the first sliding portion smoothens flow of fluid.
Since the connection structure is configured such that the valve body is accommodated within the valve cap fitted to the connection member, the number of components as well as the number of connections can be reduced. Thus, the cost of the connection structure can be reduced, and assembly work time can be shortened.
Even though the valve cap is merely fitted to the outer circumferential surface of the end part of the nipple portion of the connection member, since one end portion of the flexible tube is fitted to the outer circumferential surface of the valve cap fitted to the connection member and is further fitted to the outer circumferential surface of the nipple portion extending away from the outer circumferential surface of the valve cap, the connection can exhibit low gasoline permeability. Since no welding is required for connection of the valve cap and the end part of the nipple portion of the connection member, the cost of connection can be reduced.
In the first aspect of the present invention, instead of the first sliding portion and the first flow path portion being provided on the open end portion of the valve body, the first sliding portion and the first flow path can be provided on the inner circumferential surface of the large-diameter portion of the valve cap in the vicinity of the boundary between the large-diameter and small-diameter portions. When the upstream fluid pressure of the connection structure becomes higher than the downstream fluid pressure, so that the valve body moves toward the connection member against the compression spring, the first sliding portion provided on the valve cap allows smooth axial movement of the valve body within the large-diameter portion, and the first flow path portion provided in the first sliding portion allows smooth flow of fluid.
The first aspect of the present invention allows the valve body to further comprise a second sliding portion extending from the bottom portion away from the open end portion and accommodated slidably within the small-diameter portion of the valve cap; and a second flow path portion formed in the second sliding portion and allowing flow of fluid. The second sliding portion allows further smooth axial movement of the valve body, and the second flow path portion allows smooth flow of fluid at the second sliding portion.
In the first aspect of the present invention, instead of the first sliding portion being provided on the open end portion of the valve body or on the inner circumferential surface of the large-diameter portion of the valve cap in the vicinity of the boundary between the large-diameter and small-diameter portions, the sliding portion can be provided in such a manner as to extend from the bottom portion away from the open end portion. When the upstream fluid pressure of the connection structure becomes higher than the downstream fluid pressure, so that the valve body moves toward the connection member against the compression spring, the sliding portion allows smooth axial movement of the valve body within the small-diameter and large-diameter portions, and the flow path portion provided in the sliding portion allows smooth flow of fluid.
As described above, the first aspect of the present invention can provide the connection structure of simple structure equipped with a valve limiting flow to a single direction (a check valve) and featuring a small number of components and a small number of connections with a tube, thereby reducing the cost of a connection structure to be used in, for example, an evaporation piping system as well as assembly work time. Furthermore, even though the valve cap is merely fitted to the outer circumferential surface of the end part of the nipple portion of the connection member, since one end portion of the flexible tube is fitted to the outer circumferential surface of the valve cap fitted to the connection member and is further fitted to the outer circumferential surface of the nipple portion extending away from the outer circumferential surface of the valve cap, the connection can exhibit low gasoline permeability. Since welding is not necessarily required for connection of the valve cap and the end part of the nipple portion of the connection member, low gasoline permeability can be achieved at low cost.
According to the first aspect of the present invention, the connection structure allows a flow adjustment bore to be axially formed in the bottom portion of the valve body in such a manner as to extend through the bottom portion. When the upstream fluid pressure of the connection structure is lower than the downstream fluid pressure, a flow path, including the flow path portion is closed. However, the flow adjustment bore formed in the bottom portion of the valve body permits upstream flow of fluid of very low flow rate. When the upstream fluid pressure of the connection structure is slightly greater than the downstream fluid pressure but is not sufficiently great to move the valve body against the compression spring, the flow path including the flow path portion is closed, while fluid flows downstream at a very low flow rate through the flow adjustment bore formed in the bottom portion of the valve body. When the upstream fluid pressure of the connection structure becomes sufficiently greater than the downstream fluid pressure to move the valve body against the compression spring, the abutment part of the bottom portion of the valve body moves away from the valve seal surface and toward the connection member, thereby forming a gap between the abutment part and the valve seal surface. As a result, the flow path including the flow path portion is opened to thereby permit downstream flow of fluid of high flow rate. That is, the flow adjustment bore formed in the bottom portion of the valve body enables adjustment of the rate of downstream flow of fluid according to the difference between upstream and downstream fluid pressures of the connection structure.
According to a second aspect of the present invention, a valved connection member to be connected with a flexible tube comprises a cylindrical connection member, a cylindrical valve cap, a valve body, and a compression spring. The cylindrical connection member comprises a cylindrical nipple portion formed at one end and allowing the inner circumferential surface of an end portion of the flexible tube to be fitted thereto. The cylindrical valve cap comprises a small-diameter portion and a large-diameter portion. A valve seal surface is formed on the inner circumferential surface of the cylindrical valve cap and located between the small-diameter portion and the large-diameter portion. The cylindrical valve cap is fitted to an end part of the nipple portion of the connection member with the large-diameter portion facing the connection member. The valve body comprises a bottom portion having an abutment part to abut the valve seal surface of the valve cap. The valve body is accommodated within the large-diameter portion of the valve cap in such a manner as to be axially slidable. The compression spring is disposed between the large-diameter portion of the valve cap and the nipple portion of the connection member and adapted to bias the valve body toward the valve seal surface of the valve cap.
The valved connection member according to the second aspect of the present invention can form a connection structure through fitting of one end portion of the flexible tube to the outer circumferential surface of the valve, cap fitted to the outer circumferential surface of the end part of the nipple portion of the connection member as well as to the outer circumferential surface of the nipple portion extending away from the outer circumferential surface of the valve cap. When the upstream fluid pressure of the connection structure is lower than the downstream fluid pressure, the abutment part of the bottom portion of the valve body is in contact with the valve seal surface of the valve cap to thereby close a flow path, thereby disabling flow of fluid. In contrast, when the upstream fluid pressure becomes higher than the downstream fluid pressure, the valve body moves toward the connection member against the compression spring. Thus, the abutment part of the bottom portion of the valve body moves away from the valve seal surface and toward the connection member, thereby opening the flow path, thereby permitting downstream flow of fluid.
Since the valved connection member is configured such that the valve body is accommodated within the valve cap fitted to the connection member, the number of components required to form a connection structure as well as the number of connections can be reduced. Thus, the cost of the connection structure can be reduced, and assembly work time can be shortened.
The valved connection member is configured such that the valve cap is merely fitted to the outer circumferential surface of the end part of the nipple portion of the connection member. However, since one end portion of the flexible tube is fitted to the outer circumferential surface of the valve cap fitted to the connection member and is further fitted to the outer circumferential surface of the nipple portion extending away from the outer circumferential surface of the valve cap, the connection can exhibit low gasoline permeability. Since welding is not necessarily required for connection of the valve cap and the end part of the nipple portion of the connection member, the cost of the valved connection member can be reduced.
According to the second aspect of the present invention, a valved connection member comprises a cylindrical connection member, a cylindrical valve cap, a cylindrical valve body, and a compression spring. The cylindrical connection member comprises a cylindrical nipple portion formed at one end and allowing the inner circumferential surface of an end portion of the flexible tube to be fitted thereto; and an annular first end face portion formed at an end part of the nipple portion in such a manner as to face toward the one end and to extend radially. The cylindrical valve cap comprises a small-diameter portion and a large-diameter portion, an axial bore formed in the small-diameter portion being smaller in diameter than an axial bore formed in the large-diameter portion; a valve seat portion having a valve seal surface formed on the inner circumferential surface of the cylindrical valve cap and located between the small-diameter portion and the large-diameter portion; and a fitting end portion formed at one end of the large-diameter portion away from the small-diameter portion and fitted to the outer circumferential surface of the end part of the nipple portion of the connection member. The cylindrical valve body comprises a bottom portion having an abutment part to abut the valve seal surface of the valve cap; a cylindrical open end portion extending from the bottom portion and opening toward the connection member; an annular second end face portion formed at the open end portion in such a manner as to face the first end face portion and to extend radially; a first sliding portion extending radially outward from the open end portion in an integral condition; and a first flow path portion provided in the first sliding portion and allowing flow of fluid. The valve body is accommodated within the large-diameter portion of the valve cap in such a manner as to be axially slidable by virtue of the first sliding portion. The compression spring is disposed between the first end face portion and the second end face portion and adapted to bias the valve body toward the valve seat portion of the valve cap.
The valved connection member can form a connection structure through fitting of one end portion of the flexible tube to the outer circumferential surface of the valve cap fitted to the outer circumferential surface of the end part of the nipple portion of the connection member as well as to the outer circumferential surface of the nipple portion extending away from the outer circumferential surface of the valve cap. When the upstream fluid pressure of the connection structure becomes higher than the downstream fluid pressure, the valve body can axially move toward the connection member within the large-diameter portion of the valve cap in a smooth manner effected by the first sliding portion, and the first flow path portion provided in the first sliding portion permits smooth flow of fluid.
In the valved connection member according to the second aspect of the present invention, instead of the first sliding portion being provided on the open end portion of the valve body, the first sliding portion can be provided on the inner circumferential surface of the large-diameter portion of the valve cap in the vicinity of the boundary between the large-diameter and small-diameter portions. When the valve body moves toward the connection member against the compression spring, the first sliding portion provided on the valve cap allows smooth axial movement of the valve body within the large-diameter portion, and the first flow path portion provided in the first sliding portion allows smooth flow of fluid.
The second aspect of the present invention allows the valve body to further comprise a second sliding portion extending from the bottom portion away from the open end portion and accommodated slidably within the small-diameter portion of the valve cap; and a second flow path portion formed in the second sliding portion and allowing flow of fluid. The second sliding portion allows further smooth axial movement of the valve body, and the second flow path portion allows smooth flow of fluid at the second sliding portion.
In the second aspect of the present invention, instead of the first sliding portion being provided on the open end portion of the valve body or on the inner circumferential surface of the large-diameter portion of the valve cap in the vicinity of the boundary between the large-diameter and small-diameter portions, the sliding portion can be provided in such a manner as to extend from the bottom portion away from the open end portion. When the upstream fluid pressure of the connection structure becomes higher than the downstream fluid pressure, so that the valve body moves toward the connection member against the compression spring, the sliding portion allows smooth axial movement of the valve body within the small-diameter and large-diameter portions of the valve cap, and the flow path portion provided in the sliding portion allows smooth flow of fluid.
According to the second aspect of the present invention, there can be provided a valved connection member capable of forming at low cost a connection structure that exhibits low gasoline permeability suited for application to, for example, an evaporation piping system.
According to the second aspect of the present invention, the valved connection member allows a flow adjustment bore to be axially formed in the bottom portion of the valve body in such a manner as to extend through the bottom portion. The flow adjustment bore allows flow of fluid of a certain flow rate, which corresponds to the bore size. When the upstream fluid pressure of the connection structure becomes sufficiently greater than the downstream fluid pressure to move the valve body against the compression spring, a flow path including the flow path portion is opened to thereby permit downstream flow of fluid of high flow rate. That is, the flow adjustment bore enables adjustment of the rate of downstream flow of fluid according to the difference between upstream and downstream fluid pressures of the connection structure.